U.S. patent application number 15/998552 was filed with the patent office on 2020-09-03 for thermal metal oxide varistor circuit protection device.
The applicant listed for this patent is Dongguan Littelfuse Electronics Co., Ltd.. Invention is credited to Hailang Tang, Wen Yang, Dong Yu.
Application Number | 20200279701 15/998552 |
Document ID | / |
Family ID | 1000004865952 |
Filed Date | 2020-09-03 |
United States Patent
Application |
20200279701 |
Kind Code |
A1 |
Yang; Wen ; et al. |
September 3, 2020 |
Thermal Metal Oxide Varistor Circuit Protection Device
Abstract
A circuit protection device includes: a housing (102) defining a
cavity (130); a metal oxide varistor (110) disposed within the
cavity; a movable electrode (122) attached to a first side of the
metal oxide varistor by a solder connection (140); an arc shield
(114) disposed within the housing on the first side of the metal
oxide varistor and adjacent to the movable electrode; and a spring
(120) attached to the arc shield, wherein the arc shield is
mechanically biased against the movable electrode along a surface
direction parallel to the first side when the spring is in a
compressed state. The device is easy to assemble in lower cost and
provides fast response to overheating caused by a fault
condition.
Inventors: |
Yang; Wen; (Dongguan City,
CN) ; Tang; Hailang; (Dongguan City, CN) ; Yu;
Dong; (Dongguan City, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dongguan Littelfuse Electronics Co., Ltd. |
Dongguan City, Guangdong Province |
|
CN |
|
|
Family ID: |
1000004865952 |
Appl. No.: |
15/998552 |
Filed: |
February 15, 2016 |
PCT Filed: |
February 15, 2016 |
PCT NO: |
PCT/CN2016/073782 |
371 Date: |
August 15, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01H 61/02 20130101;
H01H 2085/0486 20130101; H01H 9/32 20130101; H01H 85/306 20130101;
H01H 85/048 20130101; H01H 2037/762 20130101; H01H 2085/381
20130101; H01H 37/761 20130101; H01H 85/36 20130101; H01C 7/126
20130101; H01H 9/16 20130101; H01H 2085/0275 20130101 |
International
Class: |
H01H 9/32 20060101
H01H009/32; H01C 7/12 20060101 H01C007/12; H01H 37/76 20060101
H01H037/76; H01H 61/02 20060101 H01H061/02; H01H 85/048 20060101
H01H085/048; H01H 85/30 20060101 H01H085/30; H01H 85/36 20060101
H01H085/36; H01H 9/16 20060101 H01H009/16 |
Claims
1. A circuit protection device comprising: a housing defining a
cavity; a metal oxide varistor disposed within said cavity; a
movable electrode attached to a first side of the metal oxide
varistor by a solder connection; an arc shield disposed within the
housing on the first side of the metal oxide varistor and adjacent
the movable electrode; and a spring attached to the arc shield,
wherein the arc shield is mechanically biased against the movable
electrode along a surface direction parallel to the first side when
the spring is in a compressed state.
2. The circuit protection device of claim 1, wherein the spring is
in a compressed state when the movable electrode is disposed over
the solder connection, and wherein when the arc shield is disposed
over the solder connection the spring is in an extended state.
3. The circuit protection device of claim 1, further comprising a
first contact lead, the first contact lead being electrically
connected to the movable electrode and a second contact lead, the
second contact lead being electrically attached to a second side of
the metal oxide varistor, the second side being opposite the first
side.
4. The circuit protection device of claim 3 further comprising a
flexible conductive wire connected between the first contact lead
and the movable electrode.
5. The circuit protection device of claim 1, wherein upon
occurrence of a fault condition where voltage exceeds a threshold
voltage of the metal oxide varistor, the metal oxide varistor is
configured to transmit electrical current adequate to heat the
solder connection to release the movable electrode, wherein the
spring displaces the arc shield over the solder connection and
displaces the movable electrode away from the solder connection
along the surface direction.
6. The circuit protection device of claim 1, further comprising an
insulator pad disposed on the first side of the metal oxide
varistor.
7. The circuit protection device of claim 6, wherein the insulator
pad comprises a printed circuit board (PCB), and wherein the arc
shield and movable electrode are disposed on the PCB.
8. The circuit protection device of claim 7, further comprising a
first contact lead, the first contact lead being electrically
connected to the movable electrode, wherein the first contact lead
extends through the housing above the PCB and does not contact the
PCB.
9. The circuit protection device of claim 8, further comprising a
flexible conductive wire connected to the movable electrode on a
first end and connected to the first contact lead on a second
end.
10. The circuit protection device of claim 1, further comprising: a
printed circuit board (PCB) disposed on the first side of the metal
oxide varistor, the printed circuit board comprising: an
electrically insulating body; an electrically conductive contact
pad disposed on a first region of the PCB; and an opening extending
between the metal oxide varistor and the movable electrode.
11. The circuit protection device of claim 10, wherein the arc
shield comprises an electrical insulator, the circuit protection
device further comprising: a pair of electrically conductive
indicator pins, wherein the pair of electrically conductive
indicator pins comprise interior ends extending within the housing
and exterior ends extending outside of the housing, wherein the
interior ends of the electrically conductive indicator pins extend
over the arc shield when the movable electrode is connected to the
solder connection, and wherein the interior ends are in electrical
contact with the electrically conductive contact pad when the
movable electrode is disconnected from the solder connection.
12. A circuit protection device comprising: a housing defining a
cavity; a metal oxide varistor disposed within said cavity; an
insulator pad disposed on a first side of the metal oxide varistor;
a movable electrode disposed on the insulator pad and electrically
connected to the metal oxide varistor; an arc shield comprising an
electrical insulator and being disposed within the housing on the
insulator pad and adjacent the movable electrode; and a spring
attached to the arc shield, wherein the arc shield is mechanically
biased against the movable electrode along a surface direction
parallel to the first side when the spring is in a compressed
state.
13. The circuit protection device of claim 12, further comprising a
solder connection extending between the metal oxide varistor and
the movable electrode via an opening in the insulator pad.
14. The circuit protection device of claim 12, further comprising:
a first contact lead, the first contact lead being electrically
connected to the movable electrode; a second contact lead
electrically attached to a second side of the metal oxide varistor,
the second side being opposite the first side; and a flexible
conductive wire connected between the first contact lead and the
movable electrode.
15. The circuit protection device of claim 12, the insulator pad
comprising: an electrically insulating body; an electrically
conductive contact pad disposed on a first region of the insulator
pad; and an opening extending between the metal oxide varistor and
the movable electrode.
16. The circuit protection device of claim 15, further comprising:
a pair of electrically conductive indicator pins, wherein the pair
of electrically conductive indicator pins comprise interior ends
extending within the housing and exterior ends extending outside of
the housing, wherein the interior ends of the electrically
conductive indicator pins extend over the arc shield when the
movable electrode is connected to the solder connection, and
wherein the interior ends are in electrical contact with the
electrically conductive contact pad when the movable electrode is
disconnected from the solder connection.
Description
TECHNICAL FIELD
[0001] Embodiments relate to the field of circuit protection
devices. More particularly, the present embodiments relate to a
surge protection device with a thermal disconnect system configured
to provide fast response to overheating.
DISCUSSION OF RELATED ART
[0002] Over-voltage protection devices are used to protect
electronic circuits and components from damage due to over-voltage
fault conditions. These over-voltage protection devices may include
metal oxide varistors (MOVs) connected between the circuits to be
protected and a ground line. MOVs have a unique current-voltage
characteristic allowing them to be used to protect such circuits
against catastrophic voltage surges. Often, these devices utilize
thermal links where the thermal links can melt during an abnormal
condition to form an open circuit. In particular, when a voltage
larger than the nominal or threshold voltage is applied to the
device, current flows through an MOV, resulting in the generation
of heat. This heat causes the thermal link to melt. Once the link
melts, an open circuit is created, preventing the over-voltage
condition from damaging the circuit to be protected. However, these
existing circuit protection devices do not provide an efficient
heat transfer from the MOV to the thermal link, thereby delaying
response times. Additionally, after an open circuit condition is
established, arcing may take place between components in close
proximity to one another. In addition, existing circuit protection
devices are complicated to assemble, increasing manufacturing
costs. Accordingly, improvements may be useful in present day
circuit protection device employing metal oxide varistors.
SUMMARY
[0003] Exemplary embodiments of the present disclosure are directed
to a circuit protection device. In an exemplary embodiment, the
circuit protection device may include a housing defining a cavity
and a metal oxide varistor disposed within said cavity. The circuit
protection device may further include a movable electrode attached
to a first side of the metal oxide varistor by a solder connection,
an arc shield disposed within the housing on the first side of the
metal oxide varistor and adjacent the movable electrode, and a
spring attached to the arc shield, wherein the arc shield is
mechanically biased against the movable electrode along a surface
direction parallel to the first side when the spring is in a
compressed state.
[0004] In another exemplary embodiment, a circuit protection device
includes a housing defining a cavity and a metal oxide varistor
disposed within said cavity. The circuit protection device may
further include an insulator pad disposed on a first side of the
metal oxide varistor and a movable electrode disposed on the
insulator pad and electrically connected to the metal oxide
varistor. In addition, the circuit protection device may include an
arc shield comprising an electrical insulator and being disposed
within the housing on the insulator pad and adjacent the movable
electrode; and a spring attached to the arc shield, wherein the arc
shield is mechanically biased against the movable electrode along a
surface direction parallel to the first side when the spring is in
a compressed state.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1A is a perspective view of a circuit protection device
in accordance with an embodiment of the present disclosure.
[0006] FIG. 1B is a cut-away perspective view of the circuit
protection device of FIG. 1A with a portion of the housing removed,
according to an embodiment of the present disclosure.
[0007] FIG. 1C is a side cross-sectional view of the circuit
protection device of FIG. 1A.
[0008] FIG. 1D is a cut-away perspective view a partially assembled
circuit protection device according to embodiments of the
disclosure.
[0009] FIG. 2A is a perspective view of an exemplary insulator pad
according to embodiments of the disclosure.
[0010] FIG. 2B is a perspective view of components of a circuit
protection device according to embodiments of the disclosure.
[0011] FIG. 2C is another perspective view of the components of a
circuit protection device of FIG. 2B.
[0012] FIG. 2D is a bottom perspective view of the components of a
circuit protection device of FIG. 2B.
[0013] FIG. 3A is a cut-away perspective view of a configuration of
the circuit protection device of FIG. 1B during normal
operation.
[0014] FIG. 3B is a cut-away perspective view of a configuration of
the circuit protection device of FIG. 1B after actuation of a fault
condition in accordance with an embodiment of the present
disclosure.
DESCRIPTION OF EMBODIMENTS
[0015] The present embodiments will now be described more fully
hereinafter with reference to the accompanying drawings, where
preferred embodiments are shown. These embodiments, however, may be
embodied in many different forms and should not be construed as
limited to the embodiments set forth herein. Rather, these
embodiments are provided so this disclosure will be thorough and
complete, and will fully convey the scope of the embodiments to
those skilled in the art. In the drawings, like numbers refer to
like elements throughout.
[0016] In the following description and/or claims, the terms "on,"
"overlying," "disposed on" and "over" may be used in the following
description and claims. "On," "overlying," "disposed on" and "over"
may be used to indicate two or more elements are in direct physical
contact to one other. However, "on,", "overlying," "disposed on,"
and over, may also mean two or more elements are not in direct
contact with one another. For example, "over" may mean one element
is above another element but not contact one another and may have
another element or elements in between the two elements.
Furthermore, the term "and/or" may mean "and", may mean "or", may
mean "exclusive-or", may mean "one", may mean "some, but not all",
may mean "neither", and/or may mean "both", although the scope of
claimed subject matter is not limited in this respect.
[0017] FIG. 1A to FIG. 1D illustrate various views of a circuit
protection device 100 according to embodiments of the disclosure.
In particular, FIG. 1A is a perspective view of the circuit
protection device 100 after assembly, not showing internal
components. The circuit protection device 100 as shown includes a
first terminal, shown as a first contact lead 104 and a second
contact lead 106. The first contact lead 104 and second contact
lead 106 extend outside a housing 102, where the housing 102 may be
an insulating material such as a known plastic material or other
polymeric material. As discussed below, the first contact lead 104
and second contact lead 106 may extend inside the housing 102 to
form electrical contact with a metal oxide varistor (MOV). The
circuit protection device 100 may also include a pair of
electrically conductive indicator pins shown as the indicator pins
108. In various embodiments the indicator pins may be electrically
connected to an electrical indicator (not shown) external to the
circuit protection device 100, such as a light or other device.
[0018] FIG. 1B is a cut-away perspective view of the circuit
protection device 100 with a portion of the housing 102 removed.
The circuit protection device 100 may include a metal oxide
varistor 110, where the metal oxide varistor 110 may have a flat
shape, such as a rectangular disc or a circular disk. The
embodiments are not limited in this context. The circuit protection
device 100 may include an insulator pad 112 disposed on the first
side (upper side parallel to the X-Y plane in FIG. 1B) of the metal
oxide varistor 110 as shown. The insulator pad 112 may be a printed
circuit board (PCB) in various embodiments. In the present
embodiments, a PCB may comprise a known material used for forming
the body of a printed circuit board. The PCB may be planar in shape
and may have any appropriate thickness for use in a circuit
protection device. In various embodiments, the PCB may further
include features such as openings or electrically conductive
material disposed on the surface of the PCB or in openings
extending through the PCB, for example.
[0019] As further shown in FIG. 1B, the circuit protection device
100 may include a movable electrode 122 disposed on the insulator
pad 112, where the operation of movable electrode 122 is discussed
below. The circuit protection device 100 may further include a
flexible conductive wire 118 connected to the movable electrode 122
on a first end and connected to the first contact lead 104 on a
second end. In various embodiments, the first contact lead 104,
second contact lead 106 and/or flexible conductive wire 118 may be
composed of a metal such as copper. The circuit protection device
100 may further include an arc shield 114 disposed within the
housing 102 on the first side of the metal oxide varistor 110 and
adjacent the movable electrode 122. The operation of the arc shield
114 is also described below. In addition, the circuit protection
device may include a spring 120, or a plurality of springs, as
shown in FIG. 1B. The spring(s) 120 may be attached to the arc
shield 114, or may otherwise engage the arc shield 114 as shown. As
illustrated in FIG. 1B, as assembled, the spring 120 may be in a
compressed state. As detailed below, this compressed state may
cause the arc shield 114 to be mechanically biased against the
movable electrode 122 along a surface direction parallel to the
first side of the metal oxide varistor 110 (i.e., along the Y-axis
of the Cartesian coordinate system shown).
[0020] Turning now to FIG. 1C there is shown a side-cross sectional
view along the direction A-A (in the X-Z plane) for the circuit
protection device 100. As illustrated, the metal oxide varistor 110
is disposed within the housing 102 and may have a first side 150
supporting the insulator pad 112, as well as a second side 152. In
plan view (X-Y plane) the metal oxide varistors 110 may be
rectangular in shape, in accordance with the shape of the housing
102, in this embodiment. As will be appreciated, alternative shapes
of metal oxide varistor 110 may also be employed and housing 102
may likewise have an alternative shape to accommodate the
particular shapes of a metal oxide varistor 110. The insulator pad
112 may be disposed directly on the metal oxide varistor 110 as
further shown in the cut-out perspective view of FIG. 1D.
[0021] The insulator pad 112, such as a PCB, may function not only
to insulate the moveable electrode and MOV but also as a protection
shield to the mechanical moving system, since in the event of a
high short circuit current, a possible flame generated from an MOV
may damage the disconnect system if no shield is present.
[0022] Additionally, the arc shield 114 may be disposed over a
portion of the insulator pad 112 as shown. In particular, the
length L of the arc shield along the direction parallel to the
Y-axis is less than the size of the cavity 130 along the Y-axis. As
detailed below this relatively smaller size of the arc shield 114
allows displacement of the arc shield 114 along the surface of the
insulator pad 112 in the direction parallel to the Y-axis,
facilitating the ability to prevent arcs during a fusing event. In
some embodiments, as further shown in FIG. 1C, the arc shield 114
may include protrusions 128 The protrusions 128 may form points of
contact to the surface of insulator pad 112, facilitating movement
of the arc shield 114 with respect to insulator pad 112 by
providing less surface area for friction between arc shield 114 and
insulator pad 112. As also illustrated in FIG. 1D, the insulator
pad 112 may include an opening 132, where the opening 132 may
accommodate a solder connection, as discussed below. In the
configuration of FIG. 1D, the arc shield 114 is positioned toward
one side of the cavity 130, opposite to the side where the first
contact lead 104 and second contact lead 106 enter the cavity 130
(See FIG. 1B). After assembly of the circuit protection device 100
for normal operation, the opening 132 of the insulator pad 112 is
situated so as to not be covered by the arc shield 144, as shown in
FIG. 1D. This opening 132 allows a solder connection to be formed
between the movable electrode 122 and metal oxide varistor 110.
[0023] FIG. 2A is a perspective view of an insulator pad 112
according to embodiments of the disclosure. In this embodiment, the
insulator pad may be a PCB having a known composition and
structure. The shape of the insulator pad 112 may be designed
according to the shape of a housing, such as a rectangular shape,
or other shape. As illustrated, the insulator pad 112 includes a
conductive contact pad 124 whose function has been described above,
as well as an opening 132.
[0024] FIG. 2B is a perspective view of components of a circuit
protection device without a housing in accordance with an
embodiment of the present disclosure. The components shown in FIG.
2A may be used in the circuit protection device 100, for example.
FIG. 2C is another perspective view of the components of a circuit
protection device of FIG. 2B. In particular, FIG. 2B illustrates
the arrangement of metal oxide varistor 110, insulator pad 112 and
first contact lead 104 and second contact lead 106. The insulator
pad 112 is disposed on the metal oxide varistors 110 and the
movable electrode 122 disposed on the insulator pad 112. The
movable electrode 122 is mechanically fixed to the metal oxide
varistor 110 by virtue of the solder connection 140. As
particularly shown in FIG. 2C the first contact lead 104 extends
over the insulator pad 112, forming a gap along the direction
parallel to the Z-axis, and does not contact the insulator pad 112.
The connection of the movable electrode 122 to the first contact
lead 104 via flexible conductive wire 118 facilitates movement of
the movable electrode 122. In particular, as discussed below with
respect to FIG. 3A and FIG. 3B, when a fault condition occurs and
the movable electrode 122 is displaced away from the side 134, the
flexible conductive wire 118 may provide little mechanical
resistance to movement of the movable electrode 122.
[0025] FIG. 2D presents a bottom perspective view of the components
of a circuit protection device of FIG. 2B. In this example, the
second contact lead 106 may terminate in a conductive pad 107 that
is electrically connected to the metal oxide varistor 110.
[0026] Turning now to FIG. 3A and FIG. 3B, there is shown an
example of operation of the circuit protection device 100 according
to embodiments of the disclosure. In FIG. 3A a cut-away perspective
view of the configuration of the circuit protection device 100
during normal operation is shown. As shown, the arc shield 114 is
positioned toward a side 134 of the cavity 130, and includes side
portions 136, where a side portion 136 engages a spring 120,
located on either side of the arc shield 114. When positioned
toward the side 134, the arc shield 114, via the side portions 136,
places the spring 120 in a compressed state. As further shown in
FIG. 3A, the movable electrode 122 abuts the arc shield 114. In
some embodiments, the movable electrode 122 may include a
protrusion such as a tab 138, engaging the arc shield 114, and
preventing the arc shield 114 from moving toward side 142. In the
configuration of FIG. 3A, the movable electrode 122 is connected to
the metal oxide varistor 110 via a solder connection 140 (shown as
dashed feature) extending through the opening 132 of the insulator
pad 112 (see FIG. 1D). The solder connection 140 may be composed of
a conventional low temperature solder in various embodiments, such
as a low melting temperature alloy including SnIn, SnBi, or other
alloy.
[0027] Because the movable electrode 122 prevents the arc shield
114 from moving, while the spring 120 is in a compressed state, the
arc shield 114 is mechanically biased against the movable electrode
122 along the Y-axis. In other words, the arc shield 114 exerts a
mechanical force against the movable electrode 122 tending to
displace the movable electrode 122 toward the side 142.
[0028] In accordance with various embodiments, the metal oxide
varistor 110 may be a conventional metal oxide varistor (MOV) made
from any appropriate composition or process. An MOV is a voltage
sensitive device designed to heat up when the voltage applied
across the device exceeds a rated voltage. By the way of
background, MOVs may be comprised of zinc oxide granules or similar
material, where the granules are sintered together to form a disc.
A given zinc oxide granule may be a highly electrically conductive
material, while the intergranular boundary is formed of other
oxides and is highly resistive. Just at those points where zinc
oxide granules meet does sintering produce a `microvaristor`
comparable to symmetrical Zener diodes. The electrical behavior of
a metal oxide varistor results from the number of microvaristors
connected in electrical series or in parallel. The sintered body of
an MOV also explains its high electrical load capacity permitting
high absorption of energy and thus, exceptionally high surge
current handling capability.
[0029] Under conventional operation, the metal oxide varistor 110
may experience a voltage across the metal oxide varistor 110 below
a threshold voltage of the metal oxide varistors 110, where the
threshold voltage corresponds to a voltage where metal oxide
varistor 110 becomes electrically conducting. Thus, when voltage is
below the threshold voltage, the metal oxide varistor 110 remains
as an electrical insulator. Conversely, when voltage across the
metal oxide varistor 110 exceeds the threshold voltage, the metal
oxide varistor may become electrically conductive. For example,
when a voltage surge condition occurs, where the voltage exceeds
the threshold voltage for a sufficient duration, the metal oxide
varistor 110 changes from a non-conductive state to the conductive
state and current flows between first contact lead 104 and second
contact lead 106. As the voltage surge continues, the gaps and
boundaries between the zinc oxide granules within the metal oxide
varistor 110 are not wide enough to block current flow, and thus
the metal oxide varistor 110 becomes highly conductive. This
conduction generates heat, causing melting of solder at the solder
connection 140. The melting of the solder, in turn, releases
movable electrode 122 from mechanical restraint formerly provided
by the bonding of the movable electrode to solid solder in the
solder connection 140.
[0030] Once mechanical constraint is released by melting of solder
in the solder connection 140, the mechanical bias provided by arc
shield 114 may displace the movable electrode 122 along the Y-axis
toward the side 142. This displacement is illustrated in FIG. 3B
FIG. 3B, showing a cut-away perspective view of a configuration of
the circuit protection device 100 after actuation of a fault
condition. As illustrated, the spring 120 is now in an extended
state, having released at least some of the potential energy stored
in the compressed state shown in FIG. 3A. The movable electrode 122
is now disposed toward the side 142, while the arc shield 114 is
disposed over the region of the solder connection 140. Movement of
the movable electrode 122 from the configuration of FIG. 3A to the
configuration of FIG. 3B may be facilitated by the tab 138,
providing a portion of movable electrode 122 easily engaged by the
arc shield 114. Because the arc shield is displaced over the solder
connection 140, any arcing otherwise produced by the high voltage
condition between the metal oxide varistor 110 and movable
electrode 122, flexible conductive wire 118, or first contact lead
104 is suppressed.
[0031] While it may be possible to solder a movable electrode
directly to a metal oxide varistor, for example, if the metal oxide
varistor is coated with insulation material, e.g. epoxy, etc, such
a design may not withstand a high short circuit current during
overvoltage events as well as designs using the insulator pad 112
of the aforementioned embodiments. Accordingly, the embodiments
employing an insulator pad 112 may provide better protection
against flame damage caused by a high short circuit current in
compared to a configuration in which the movable electrode and arc
shield are directly adjacent a metal oxide varistor.
[0032] In various embodiments, the indicator pins 108 may be
configured to provide an indication of a fault condition. As shown
in FIG. 3A and FIG. 3B the indicator pins may have interior ends
extending within the housing 102 and exterior ends extending
outside of the housing 102. In the configuration of FIG. 3A, the
indicator pins may extend over the arc shield 114 when the movable
electrode 122 is connected to the solder connection 140 as shown.
In particular, the interior ends 108A (see FIG. 3B) of the
indicator pins 108 may be mechanically biased downwardly along the
Z-axis toward the arc shield 114. Because the arc shield 114 is an
electrical insulator, the indicator pins 108, even if contacting
the surface of the arc shield 114, are not electrically connected
to one another and accordingly do not complete an electrical path.
During a fault condition where the arc shield 114 is displaced away
from the side 134, a portion of the insulator pad 112 adjacent the
side 134 is exposed. In various embodiments, the insulator pad 112,
such as a PCB, may include on the outer surface an electrically
conductive contact pad 124, located towards the side 134 as shown.
This location allows the indicator pins 108, being mechanically
biased toward the insulator pad 112, to form electrical contact
with the electrically conductive contact pad 124 when the movable
electrode 122 is disconnected from the solder connection 140 and
the arc shield is accordingly displaced toward the side 142. The
indicator pins 108 may accordingly complete an electrical path
forming part of a circuit including an indicator light (not shown)
or other device, and accordingly providing an indication of a fault
condition.
[0033] In summary, the circuit protection devices of the present
embodiments provide a novel configurations of components for
response to an overvoltage conditions. The circuit protection
devices are designed to provide a thermally driven disconnect
system harnessing the heating of an MOV under a fault condition.
Among other advantages, the present embodiments provide a device
easy to assemble, providing lower cost. The circuit protection
devices also provide fast response to overheating caused by a fault
condition. In some embodiments, up to 200 kA may be passed without
use of additional protection. The circuit protection devices
further provide a safe disconnecting device free from arcing issues
in a compact package. In addition, a convenient fault or isolation
indication is provided.
[0034] While the present embodiments has been disclosed with
reference to certain embodiments, numerous modifications,
alterations and changes to the described embodiments are possible
without departing from the sphere and scope of the present
embodiments, as defined in the appended claims. Accordingly the
present embodiments are not to be limited to the described
embodiments, but have the full scope defined by the language of the
following claims, and equivalents thereof.
* * * * *